Electric water heater



Aug. 4, 1936. L. P. HAUSSAUER ELECTRIC WATER HEATER Filed Nov. 5, 1935 IIVVEIVEI? L.Eflzussaaez;

Patented Aug. 4, 1936 v UNITED s'rArEs ELECTRIC WATER HEATER Louis Paul Haussauer, London, England Application November 5, 1935,- 'SerialNo. 48,368

In Great Britain April 30, 1935 3 Claims.

This invention has reference to electric heaters of the immersion type, which comprise a resistor enclosed in and electrically insulated from a metal sheath.

In accordance with this invention there is provided an electric immersion unit which comprises a heater of the type defined mounted. within a jacket closed top and bottom and having a nonreturn valve disposed above the heater and con 10 trolling a vent which opens to atmosphere, the jacket containing a heat conducting medium up to a level above the heater and below the valve so as to leave space for expansion of the medium.

A suitable heat conducting medium is mineral oil having a higher boiling point than water and the use of the valve which normally closes the vent allows air to escape when the oil is first being heated and prevents the admittance of a new supply of air. Thus a partial vacuum is created in the expansion space which prevents the deterioration of the medium.

In the preferred construction of the unit, the vent pipe is bent back to pass through the base plate which closes the bottom of the jacket and carries the heater, and for the purpose of condensing any fumes which may have passed the valve the vent pipe between the valve and the vent outlet may be provided with a coiled portion, although the coil is not altogether necessary in certain sizes of heaters.

As the temperature of the jacket will be lower than that of the metal sheath of the resistor, the invention in embodying the usual thermostatic control for the heater, mounts the stem of the thermostat in direct metallic contact with the jacket, and thus the thermostat will operate even when the container in which the unit is placed is empty of water. Consequently damage to the heater is avoided at all times.

In order to describe the invention more fully, a sheet of drawings is appended, wherein:--

Figure 1 is an elevation, partly in section, of an electric immersion unit according to one embodiment of the invention; and

Figure 2 is an enlarged sectional view of the domed top of the heater jacket, showing more particularly the construction of the non-return valve.

Referring to the drawing, the unit comprises a base plate I which is adapted. to be fitted to the bottom of a water container in any suitable way. The container (which is not shown) is furnished with a cold water inlet and a hot water outflow of any suitable design.

Through the base plate I are mounted heaters 2 of the type above defined, which are encased by the domed jacket 3, the bottom of which is closed by the base plate I. The jacket is partly filled with mineral oil 4 up to a level above heaters 2 but below the top of the jacket so as to 5 leave a space i in which the oil can expand when heated. Also through the base plate I is mounted the thermostat stem 5 in contact with the jacket 3, the thermostat itself being indicated at 6.

In the top of the jacket is provided a nonreturn valve 1 (Figure 2) which is normally kept closed by a spring i and controls a vent pipe 8 which opens to atmosphere by being bent back to pass through the base plate I, this pipe having 5 a coiled portion 8 between the valve and its outlet to atmosphere for the purpose of condensing any fumes which might pass the valve 1. In addition to its other functions the valve 1 serves to prevent oil passing into the vent pipe as the jacket is charged through a hole in the base plate, and further, prevents spilling of the oil during transit of the unit.

A safety disc 9 may be incorporated in the jacket wall near the base plate I. This is advantageously a brass disc soft soldered over a hole in the jacket and is intended to fuse loose and fall in the double event of the main water container being empty and the thermostat failing to function when in the on position. Also should the oil attain too high a temperature (e. g. 600 degrees Fahr.) the safety device would come into action and allow the oil to escape through the hole ordinarily covered by the disc 9.

It is understood that the heat conductive medium may be selected from a large range of substances, although oil is the preferred medium.

In use the unit will effect a gentle heating of the water in the container, the surface temperature of the jacket being less than that of the metal sheath of the resistor whilst the useful heating area is increased andconsequently only a slight amount of fur results which does not cling to the jacket but is of a soft precipitate nature which tends to settle at the bottom of the water chamber. The efficiency of the type of heaters employed is thereby maintained or increased, and efiicient operation without the frequent dismantling of the apparatus for replacement or repair of internal parts, is also ensured. Two immersion heaters 2 are shown in the accompanying drawing, and due to their use inside the jacket a strong circulation of the oil is created, the consequence being a uniformity of heat all over the jacket. With bare immersion heaters the maximum heat is at the top, whereas with the oil circulation the bottom of the jacket is almost as hot as the top. This again results as less furring effect.

I claim:

1. An electrical immersion heating unit for disposition within a receptacle to contain liquid to be heated, said unit comprising a closed jacket having a vent opening in the top thereof, an electrical heating element within said jacket, a liquid within said jacket having a higher boiling point than water, there being an air space between the surface of the liquid in said jacket and said vent, and an outwardly opening yieldably closed check valve controlling said vent opening.

2. An electrical immersion heating unit as set forth in claim 1 including a tube leading from said vent opening and having a condensing coil therein.

3. An electrical immersion heating unit for disposition within a receptacle to contain liquid to be heated, said unit comprising a vertically disposed closed jacket having a vent opening in the top thereof, an electrical heating element within said jacket, the uppermost part of said element being disposed below the top of the jacket, a heat conducting liquid within said jacket having a level above the top of said heating element and below the top of the jacket, and an outwardly opening yieldably closed check valve controlling said vent opening.

LOUIS PAUL HAUSSAUER. 

